This would be a really cool addition to HoI2. Having the ability to build in your provinces factories for war items like airframes, ammunition, airplane engines, tanks, ball bearings, aviation fuel, jet fuel, tires, machine guns, rolled steel, auto parts, aviation parts, naval hulls, naval engines, and so on. This would simulate a wartime economy and allow for excellent strategising in bomber raids. For example, the Schweinfurt raid, which was meant to destroy much of Germany's ball-bearing production. Had the raid been more successful, it would have slowed down German industrial production significantly. These goods would supply your ability to build units in the game.
Arado
Arado